Diastereomeric Fullerene Composite Engineering for Enhanced Perovskite Solar Cells.

Achieving high performance and long-term stability in perovskite solar cells (PSCs) typically requires the use of surface passivation layers to suppress the interfacial defects. However, these additional passivation agents often introduce chemical and structural instabilities, limiting the device lifetime. Here, we present a molecular engineering strategy utilizing a chiral series of C-Furan-Sugar (CFS) fullerene derivatives blended with [6,6]-phenyl-C-butyric acid methyl ester (PCBM) to modify the electron transport layer (ETL).

Mesoscopic Structure of Lipid Nanoparticle Formulations for mRNA Drug Delivery: Comirnaty and Drug-Free Dispersions.

Lipid nanoparticles (LNPs) produced by antisolvent precipitation (ASP) are used in formulations for mRNA drug delivery. The mesoscopic structure of such complex multicomponent and polydisperse nanoparticulate systems is most relevant for their drug delivery properties, medical efficiency, shelf life, and possible side effects. However, the knowledge on the structural details of such formulations is very limited.

Isolated Rh atoms in dehydrogenation catalysis.

Isolated active sites have great potential to be highly efficient and stable in heterogeneous catalysis, while enabling low costs due to the low transition metal content. Herein, we present results on the synthesis, first catalytic trials, and characterization of the GaRh phase and the hitherto not-studied GaRh phase. We used XRD and TEM for structural characterization, and with XPS, EDX we accessed the chemical composition and electronic structure of the intermetallic compounds.

A New Class of Task-Specific Imidazolium Salts and Ionic Liquids and Their Corresponding Transition-Metal Complexes for Immobilization on Electrochemically Active Surfaces.

Adding to the versatile class of ionic liquids, we report the detailed structure and property analysis of a new class of asymmetrically substituted imidazolium salts, offering interesting thermal characteristics, such as liquid crystalline behavior, polymorphism or glass transitions. A scalable general synthetic procedure for N-polyaryl-N'-alkyl-functionalized imidazolium salts with para-substituted linker (L) moieties at the aryl chain, namely [LPh Im R] (L=Br, CN, SMe, CO Et, OH; m=2, 3; R=C , PEG ; n=2, 3, 4), was developed. These imidazolium salts were studied by single-crystal X-ray diffraction (SC-XRD), NMR spectroscopy and thermochemical methods (DSC, TGA).

Effect of Bromide on the Surfactant Stabilization Layer Density of Gold Nanorods.

Some studies have speculated that the concentration of bromide ions plays a crucial role in the surfactant density surrounding gold nanorods (AuNR). Small-angle X-ray and neutron scattering (SAXS and SANS) experiments were conducted to analyze any influence the bromide ions might have on the stabilization layer and the aggregation behavior of the ligand CTAB molecules in general. The AuNR were immersed in solutions containing a fixed CTA concentration of 2 mM and varying bromide ion concentrations from 0 to 22 mM.

Photo-Initiated Cobalt-Catalyzed Radical Olefin Hydrogenation.

Outer-sphere radical hydrogenation of olefins proceeds via stepwise hydrogen atom transfer (HAT) from transition metal hydride species to the substrate. Typical catalysts exhibit M-H bonds that are either too weak to efficiently activate H or too strong to reduce unactivated olefins. This contribution evaluates an alternative approach, that starts from a square-planar cobalt(II) hydride complex.

A Self-Ordered Nanostructured Transparent Electrode of High Structural Quality and Corresponding Functional Performance.

The preparation of a highly ordered nanostructured transparent electrode based on a combination of nanosphere lithography and anodization is presented. The size of perfectly ordered pore domains is improved by an order of magnitude with respect to the state of the art. The concomitantly reduced density of defect pores increases the fraction of pores that are in good electrical contact with the underlying transparent conductive substrate.

Lipid Dynamics in Membranes Slowed Down by Transmembrane Proteins.

Lipids and proteins, as essential components of biological cell membranes, exhibit a significant degree of freedom for different kinds of motions including lateral long-range mobility. Due to their interactions, they not only preserve the cellular membrane but also contribute to many important cellular functions as e.g.

Interface between Water-Solvent Mixtures and a Hydrophobic Surface.

The mechanism behind the stability of organic nanoparticles prepared by liquid antisolvent (LAS) precipitation without a specific stabilizing agent is poorly understood. In this work, we propose that the organic solvent used in the LAS process rapidly forms a molecular stabilizing layer at the interface of the nanoparticles with the aqueous dispersion medium. To confirm this hypothesis, -octadecyltrichlorosilane (OTS)-functionalized silicon wafers in contact with water-solvent mixtures were used as a flat model system mimicking the solid-liquid interface of the organic nanoparticles.

X-ray characterization of physical-vapor-transport-grown bulk AlN single crystals.

AlN slices from bulk crystals grown under low thermomechanical stress conditions via the physical vapor transport (PVT) method were analyzed by X-ray methods to study the influence of the growth mode on the crystal quality. Defect types and densities were analyzed along axial [0001] as well as lateral growth directions. X-ray diffraction (0110) rocking-curve mappings of representative wafer cuts reveal a low mean FWHM of 13.

A novel experimental approach for nanostructure analysis: simultaneous small-angle X-ray and neutron scattering.

Exploiting small-angle X-ray and neutron scattering (SAXS/SANS) on the same sample volume at the same time provides complementary nanoscale structural information in two different contrast situations. Unlike an independent experimental approach, the truly combined SAXS/SANS experimental approach ensures the exactness of the probed samples, particularly for studies. Here, an advanced portable SAXS system that is dimensionally suitable for installation in the D22 zone of ILL is introduced.

Unraveling the Microstructure-Related Device Stability for Polymer Solar Cells Based on Nonfullerene Small-Molecular Acceptors.

As the power conversion efficiency (PCE) of organic solar cells (OSCs) has surpassed the 17% baseline, the long-term stability of highly efficient OSCs is essential for the practical application of this photovoltaic technology. Here, the photostability and possible degradation mechanisms of three state-of-the-art polymer donors with a commonly used nonfullerene acceptor (NFA), IT-4F, are investigated. The active-layer materials show excellent intrinsic photostability.

Internal Structure of Nanometer-Sized Droplets Prepared by Antisolvent Precipitation.

Antisolvent precipitation (AP) is a low-cost and less-invasive preparation alternative for organic nanoparticles compared to top-down methods such as high-pressure homogenization or milling. Here we report on particularly small organic nanoparticles (NPs) prepared by AP. It has been found for various materials that these NPs in their liquid state exhibit a significant degree of molecular order at their interface toward the dispersion medium including ubiquinones (coenzyme Q10), triglycerides (trimyristin, tripalmitin), and alkanes (tetracosane).

Multimodeling Approach to Ferromagnetic Spin-Wave Excitations in the High-Spin Cluster MnSr Observed by Inelastic Neutron Scattering.

The magnetism of the mixed-valence high-spin cluster [MnSrO(N)Cl(MedhmpH)(MeCN)]Cl () exhibiting intramolecular ferromagnetic interactions was studied using inelastic neutron scattering (INS), and reliable values for the exchange coupling constants were determined based on the quality of simultaneous fits to the INS and magnetic data. The challenge of the huge size of the Hilbert space (3 375 000) and many exchange coupling constants (7 assuming a symmetry) generally encountered in large spin clusters was resolved as follows: (a) The results of the restricted Hilbert space ferromagnetic cluster spin wave theory were compared to the experimental spectroscopic data. The observed INS transitions were thus assigned to spin wave excitations in a bounded ferromagnetic spin cluster and moreover could be visualized in a straightforward way based on this theory.

Comprehensive Investigation and Analysis of Bulk-Heterojunction Microstructure of High-Performance PCE11:PCBM Solar Cells.

Worldwide research efforts have been devoted to organic photovoltaics in the hope of a large-scale commercial application in the near future. To meet the industrial production requirements, organic photovoltaics that can reach power conversion efficiency (PCE) of over 10% along with promising operational device stability are of utmost interest. In the study, we take PCE11:PCBM as a model system, which can achieve over 11% PCE when processed from nonhalogen solvents, to deeply investigate the morphology-performance-stability correlation.

Overcoming efficiency and stability limits in water-processing nanoparticular organic photovoltaics by minimizing microstructure defects.

There is a strong market driven need for processing organic photovoltaics from eco-friendly solvents. Water-dispersed organic semiconducting nanoparticles (NPs) satisfy these premises convincingly. However, the necessity of surfactants, which are inevitable for stabilizing NPs, is a major obstacle towards realizing competitive power conversion efficiencies for water-processed devices.

Concentration dependent morphology and composition of n-alcohol modified cetyltrimethylammonium bromide micelles.

Cetyltrimethylammonium bromide (CTAB) is one of the most commonly used surfactants in nanoparticle synthesis and stabilization. Usually, CTAB is used in high concentrations besides co-surfactants leading to well defined products but the complex mesoscopic CTAB structures stay mostly unknown. N-alcohols for instance are widely used co-surfactants which modify the properties of native CTAB dispersions.

Unravelling the Mechanisms of Gold-Silver Core-Shell Nanostructure Formation by in Situ TEM Using an Advanced Liquid Cell Design.

The growth of silver shells on gold nanorods is investigated by in situ liquid cell transmission electron microscopy using an advanced liquid cell architecture. The design is based on microwells in which the liquid is confined between a thin SiN membrane on one side and a few-layer graphene cap on the other side. A well-defined specimen thickness and an ultraflat cell top allow for the application of high-resolution TEM and the application of analytical TEM techniques on the same sample.

Robot-Based High-Throughput Engineering of Alcoholic Polymer: Fullerene Nanoparticle Inks for an Eco-Friendly Processing of Organic Solar Cells.

Development of high-quality organic nanoparticle inks is a significant scientific challenge for the industrial production of solution-processed organic photovoltaics (OPVs) with eco-friendly processing methods. In this work, we demonstrate a novel, robot-based, high-throughput procedure performing automatic poly(3-hexylthio-phene-2,5-diyl) and indene-C bisadduct nanoparticle ink synthesis in nontoxic alcohols. A novel methodology to prepare particle dispersions for fully functional OPVs by manipulating the particle size and solvent system was studied in detail.

Excitons and Trions in One-Photon- and Two-Photon-Excited MoS : A Study in Dispersions.

Herein, various dispersions of MoS obtained by means of liquid phase exfoliation are spectroscopically, (spectro-) electrochemically, and microscopically characterized. At the core of these studies are transient absorption assays. Importantly, small-angle X-ray scattering measurements are employed to corroborate the exfoliated character of the MoS flakes in dispersion, on the one hand, and to correlate the results with TEM, AFM, and Raman characterization in the solid state, on the other.